restore composer.json, add mysqli extension

app/Http/Controllers/Payments/key_model.php

@@ -0,0 +1,13 @@
+<?php
+    $id = (int) $key;
+
+    $billing = \App\Models\Billing::find($id);
+    if (!empty($billing)) {
+        if ($billing->status == 'waiting') {
+            return $billing;
+        }
+    }
+
+
+    return null;
+